The invention pertains to a stacking device for a flat, upright mail pieces.
In sorting stations for flat mail pieces, e.g., letters, postcards and the like, stacks of mail pieces are decollated in order to carry out the subsequent sorting process as well as combined into stacks, e.g., in stacking compartments that lie adjacent to one another. In this case, the flat mail pieces are transported while being clamped between cover bands and stacked in an upright position.
The stack being formed needs to be held opposite to the supply side of the mail pieces such that it does not overturn. Supports that can be displaced in the stacking direction are used for this purpose. Different variations are available for controlling the displacement process. For example, the thicknesses of the mail pieces to be stacked are measured and the support is correspondingly displaced away from the stacking point by means of a drive.
In an inexpensive variation, the mail pieces are obliquely transported to the stacking point in the direction of the support. Due to the force component in the stacking direction, the support is displaced away from the stacking point against the force of a spring that acts in the direction of the stacking point.
Once the stack has reached its nominal size, the support is laterally tilted such that the stack can be pushed out of the stacking compartment in an unobstructed fashion. In order to prevent the support being moved into the region of the adjacent stacking compartment, the support cannot exceed a certain size. After the stacking compartment is emptied, the support is pushed or pulled toward the stacking point by the force of a spring.
If the mail pieces to be stacked have different sizes, the stack begins to overturn once a certain stack thickness is reached because the larger mail pieces tilt over the relatively small support. An elevated arrangement of the support is not possible because the smaller, flexible mail pieces would otherwise slide through underneath the support.
Consequently, the invention is based on the objective of developing a stacking device for flat, upright mail pieces of different sizes with a support of limited size which holds the stack and can be displaced in the stacking direction, and with a stacking point, at which the mail pieces are stacked in an orderly pattern without being tilted.
At the beginning of the respective stacking process, the relatively small support is situated in a lower position, in which small and flexible mail pieces cannot slide through underneath the support and large mail pieces can still be held. In order to prevent tilting of the large mail pieces over the support as the thickness of the stack increases, the support is gradually moved into an elevated position, in which the upper portion of the support is situated above the center of gravity of the largest mail piece and the lower portion of the support is situated underneath the upper edge of the smallest mail piece. Due to the no longer flexible stack, the small mail pieces are no longer able to slide through underneath the support. As used herein, the term xe2x80x9clarge mail piecexe2x80x9d refers to a mail piece that is significantly larger than the inner face of the blade of the support as best shown in FIG. 2, and is therefore likely to tip over the support during the stacking process.
Since large mail pieces, depending on the array, frequently begin to tilt only once a certain stack thickness is reached, the upward movement of the support advantageously takes place only once a selectable stack thickness is reached. The movement of the support from the lower position into the upper position can be advantageously realized in the form of a pivoting movement. In this case, it is advantageous to arrange the support in a pivoted fashion on the displacement path, namely in the same horizontal position, and to guide the support outside of the pivoting point by means of an ascending rail in such a way that the support is pivoted upward during the displacement in the stacking direction.
In another aspect, the invention provides a stacking device for mail pieces that includes a guide aligned in the direction of stacking of the mail pieces, a support having a blade for supporting a stack of flat, upright mail pieces by engaging an endmost mail piece, the support being moveable along the guide as mail pieces are stacked to retain the mail pieces in the stack, and a pivot mechanism including a bearing that is connected to the guide and pivotally mounted on the guide, which pivot mechanism causes the support to pivot upwardly at one end thereof adjacent the guide when the support reaches a predetermined position along the guide. The pivot mechanism causes the support to pivot upwardly at one end thereof adjacent the guide when the support reaches a predetermined position along the guide, thereby better supporting the stack of mail as described above.
In another advantageous embodiment, no pivoting movement takes place. In this case, the support remains in the same pivoting position, and the bearing point of the support is moved upward as the stack thickness increases. For example, instead of using an inclined rail as part of the pivot mechanism as described hereafter, the guide could be set at an incline so that the entire support assembly moves upwardly while maintain a horizontal position as the stack thickens.
The invention is described in greater detail below with reference to one embodiment that is illustrated in the figures.